1. Field of Invention
The present invention generally relates to a laminated substrate structure and the manufacture method thereof, and more particularly, to a package substrate or Printed Circuit Board (PCB) structure and the manufacture method thereof.
2. Description of Related Art
In line with fast growth and the high demand for electronic technology, the development of electronic products tends towards miniaturization and high density integration. In the packaging field, the development of the Ball Grid Array (BGA) and Chip Scale Package (CSP) is targeted at the market requirements for miniaturization and high-density integration. For the Printed Circuit Board (PCB), in order to minimize the circuit area used, the technology of the multi-layered structure is applied. However, the substrate used in BGA, CSP and the manufacture of PCB all uses vias that are made of conductive material to connect between layer circuits. Therefore, the fine trace circuit on the laminated substrate and the small dimension vias can improve the package density and the PCB integration.
The conventional laminated substrate manufacture method is mainly divided into two categories: lamination process and build up process. The lamination process provides a plurality of isolation layers first, then forms a circuit layer on the surface of the isolation layers, and performs the drill, plate, and hole plugging process on each isolation layer to form a plating through hole (PTH), so that the circuit layer on the surface of the isolation layer is electrically coupled by the plating through hole formed by the via process. After the via is formed in each isolation layer, the conductive circuit is subsequently formed on the laminated surface copper layer. Afterwards, the substrate or the circuit board is made by repeatedly performing a process that comprises aligning a determined number of the isolation layers to the surface copper layer, laminating them into a laminated substrate, and forming a conductive circuit.
When the laminated substrate is made by using the conventional lamination process, the via forming, plating through hole and the isolation material hole plugging operations must be performed on the isolation layer, and the process is rather sophisticated and time consuming. Moreover, the process difficulty and unit cost significantly increase accordingly when the isolation layer via dimension approaches 100 micrometers or below. When the via dimension is less than 100 micrometers or below, there is as yet no mass production product provided by vendors. Therefore, there is a mass production technology bottleneck problem when the plating through hole is less than 100 micrometers.
Besides the lamination process, the build up process is also broadly adopted by vendors. The build up process mainly forms the dielectric layer, the inter-layer via in the dielectric layer, and the circuit layer on the surface of the dielectric layer sequentially from bottom to over both sides of the laminated core substrate. The dielectric layer in the laminated substrate is mainly formed by using the lamination or coating method. After the dielectric layer is formed, an opening is formed in the dielectric layer by using the image forming/etching process or the laser/plasma etch method, and the inter-layer via is formed by filling the conductive material into the opening or by using the plating method. After the inter-layer via is formed, a sophisticated chemical surface process is performed and the circuit layer is formed on the surface of the dielectric layer. The laminated substrate is formed by repeatedly performing the sophisticated and difficult manufacture steps of the dielectric layer, inter-layer via, chemical surface process, and forming the circuit layer.
In the substrate formed by the build up process, each dielectric layer and circuit layer has to be formed sequentially, so that the whole process is too lengthy. Moreover, the quality of forming each dielectric layer and circuit layer directly impacts the yield of the whole building substrate, thus it is not easy to control the process yield. When the substrate is formed by the build up process, besides the problem of the lengthy process and the low process yield, it also has the problems of high process cost and big equipment investment cost, or the reliability deteriorates due to the process not being easy to control.
FIG. 1 schematically shows a sketch view of the contact position of the circuit layer and the via in the conventional laminated substrate structure, wherein the contact position has a via land. Referring to FIG. 1, a circuit 100a and a via land 102a are isolated from a circuit 100b and a via land 102b by a dielectric layer (not shown). The dimensions of the via land 102a, 102b are usually designed to be wider than the linewidth of the circuit 100a, 100b, so as to assure that two circuit layers are electrically coupled by the via 104 in the dielectric layer. However, the via land 102a and the via land 102b usually reduce the layout space of the circuit layer, so that the circuit density in the laminated substrate cannot be efficiently improved.